Many workpieces have internal or external splines and are usually designed to mate or slidably interfit with complementary external or internal splines on another workpiece. In many manufacturing and assembly operations, and particularly automated operations, it is necessary to accurately measure the splines of many workpieces of the same nominal size. The spline is usually measured by gauges which measure either the pitch diameter of the spline or the thickness of a tooth or teeth of the spline.
Even in mass production operations, the splines have been measured by gauges which are manually held and manipulated. The gauge and spline are manually held and manipulated because of difficulty in aligning and inserting the spline in the gauge and the great likelihood of damaging the spline and/or the guage if they are improperly aligned or jammed together. In many manufacturing operations, the exact size of the spline is not measured and it is merely determined whether the spline size is within predetermined limits by utilizng both a "go" gauge and a separate "no go" gauge for each spline of each workpiece. This requires the manual operations of inserting and removing two gauges for each workpiece.
In other applications, the size of the spline is measured by a manual gauge which has at least two sensing elements which are inserted in a groove between adjacent teeth of the spline and then relatively rotated to bear on portions of the opposed side faces of the teeth defining the groove. These gauges can be constructed to measure either the actual size or the effective size of the spline. For measuring the effective size, the elements are arranged in a full circle and project into all of the grooves of the spline, and hence provide a measurement of the size of the spline under operating conditions in which it mates with a complementary spline of another workpiece. When constructed to measure the actual size of the spline, the elements of the gauge project into only a few essentially diametrically opposed grooves of the spline and engage only a few of its essentially diametrically opposed teeth.